Meter for indicating ratio of fluid fuel consumption to engine speed



Feb. 18, 1936- w. F. SUTHERLAND ET AL 2,031,192

METER FOR INDICATING RATIO OF FLUID FUEL CONSUMPTION T0 ENGINE SPEED Filed Oct. 27, 1933 wIIIIIII/ nnuna Patented Feb. 18, 1936 UNITED STATES METER FOB INDICA'IING RATIO OF FLUID FUEL CONSUMPTION T0 ENGINE SPEED William I. Sutherland and Grlfiln G. Waite, Toronto. Ontario, Canada Application October 27, 1933, Serial No. 695,480

serum.

The principal objects of the invention are, to enable the person operating an engine of the variable or constant speed type to ascertain the ratio of the rate of flow of fuel to the engine speed. thus enabling him to determine whether or not the engine is operating efilciently.

The principal feature of the invention consists in the novel arrangement of a gauge communicating with the pressure chamber of the engine operated fuel pump, whereby the pressure in the pump body. indicated by the gauge. will give a measure of fuel consumption in relation to engine revolutions, which in the case of vehicles operating on land may be indicated in terms of miles per gallon.

In the accompanying drawing, Figure 1 is a diagrammatic sectional view of a fluid fuel pump for use in supplying fuel to a fluid fuel motor and equipped with our improved gauge arrangement.

Figure 2.is an enlarged detail of a portion of the pipe connection between the fuel pump and the gauge.

Figure 3 is an enlarged elevational view of the gauge.

Figure 4 is a part sectional view showing the indicator fingers of the gauge.

In the operation of internal combustion engines it is now common practice to feed the liquid fuel to the carburetor by means of a pump actuated by the engine movement.

In the form of pump device illustrated in Figure 1, i represents the engine cam shaft which carries a cam 2 which is in constant engagement with a rocker member 3 pivotally mounted at l and having a forked or slotted end i.

A rod 6 is slidably mounted in suitable supports and passes through the forked or slotted end of the member 3 and is connected by a pair of toggle link members 1 and I to-the stem I of the 0 pump Ill.

A diaphragm ii is arranged to extend across the pump casing and the spindle O is surmounted by a cap If which is secured to the diaphragm II and said spindle in its reciprocatio'ns operates the 5 diaphragm against the coiled compression spring II surrounding the spindle e.

A stop member II is fixedly mounted on the rod below the forked end 5 of the member I, so that as the cam I rotates and swings the rocker member a on its pivot the slo'tted end e engages the invention consists in connecting to the pump As the cam 2 operates the rocker arm. swinging the end I thereof downwardly to engage the stop ll, it pulls downwardly on the spindle 9 and consequently upon the diaphragm to which the cap I! is secured. 5

The upward movement of the rocker arm does not displace the spindle '9 as the toggle links I and 8 break Joint automatically upon the cessation of a downward pull thereagainst.

The pump In is provided with an inlet valve ii and an outlet valve ll.

The downward movement of the spindle 0 draws liquid into the pump chamber and the return movement of the diaphragm effected by the spring i3 expels liquid through the outlet valve ll.

It will be understood that a pulsating or reciprocating motion of the diaphragm ii is created which is of a frequency directly proportional to the engine speed and the alternating pulsation creates an alternating vacuum and pressure 20 in the pump body causing the fuel to flow.

It will also be understood that the travel of the spindle I is variable in accordance with the movement of the diaphragm ii and its mean position with respect to the remainder of the pump is dependent on the mean pressure in the pump body.

As the pressure increases the spindle is forced downward. The toggle link I. 8 is collapsed to an increasing degree and the rod 6 has to straighten the toggle before it can act to operate upon the spindle 9 and diaphragm II which thus regulates the stroke of the diaphragm.

As the pressure within the pump decreases the movement of the toggle members is lessened and consequently a greater amount of the travel of the spindle 9 is effective in imparting a greater amplitude of displacement to the diaphragm.

This type of pump is well known in the art and casing at a point above the diaphragm a tube II which connects with the "Bourdon" tube of a pressure gauge I9, the indicator finger of which indicates a measure of fuel consumption in direct relation to engine revolutions and where the engine is arranged on a vehicle operated on land such revolutions are directly proportional to speed consequently where there is fixed fuel flow the greater the speed of revolution the greater number of pulses per second, which results in the lowering of the mean position'of the diaphragm consequent upon a greater pressure.

The higher the flow of fuel with the speed remaining constant the greater will be the displacement per pulse, resulting in the higher position of the diaphragm and a lower pressure.

Let p=spring gradient in pounds per unit area of diaphragm per unit length of stroke.

L=totai deflection to free unloading of spring. This is not total length of stroke, since diaphragm is constrained by cam and spring canthus be. considered as pre-loaded for full stroke of pump.

l=actual length of stroke for any given delivery per stroke. 1

P=pressure corresponding to 1 above.

To every stroke the vehicle travels a definite distance and therefore the volume pumped per stroke is a measure of the gallons per mile (multiplied by a constant). Likewise, since the piston area of the pump is constant, the length of stroke is also a measure of the gallons per mile, or gallons per mile=Kl where K is a constant.

The pressure P effective in governing the length of the stroke and consequently the delivery per stroke is that pressure in the pump chamber equal and opposite to the force set up by the compression of the spring. This force set up by the spring for any given stroke lis equal to the spring gradient p times the diii'erence between the free spring length L and the stroke 1. or:

and v N I 1 Y P gallons per mile=K(L or gallons-per mile'= K1 KzP where 31 and K1 I miles per gailon= damping which may be produced by'mountingan inertia member I! to swing with the pointer 20 so that the pulses from thefuel pump will not resonate with the moving parts of the gauge.

It may be found desirable to effect the same result in the gauge by providing one'or more con strictlons ii in the tube it between the gauge and the pump. as is illustrated in Figure}.

This invention'permits the checking-up of performance of the engine over long periods of time and the gauge is preferably provided withan in dicator finger 22 which may be manually resetbut is moved-to retain an indication of the highest previous efficiency obtained. v Figures 3 and 4 illustrate a gauge capable of showing these features. The pointer 22 is attached to'a knurled nuns and is adapted to be turned by hand and held in position by a shaft through the gauge glass and a suitable friction device. of the well known bowed spring type which draws the nut It axially to frictional contact with the surface of the gauge glass. This v indicator finger 22 is spaced from the gauge pointer II, and if desired, the pointer 2| maybe provided with an operating extension 2| which will engage the pointer 22 to move same to a maximum indicating position in a manner which is well known in the metering art.

As the gauge is susceptible to the influence of the combined pressure in the pump and the pulsations thereof, the direct effect of the mean condition is indicated by the operation of the auge finger 2|.

' A meter for indicating ratio of fluid consumption to engine speed is not only applicable to vehicles operating on land and giving accurate miles per gallon readings, but it may be applied to both water, air and other forms of transport or with other applicationsof engines where the readings of fluid flow in proportion to engine speed will be quite dependable under normal conditions of operation. In all instances the gauge, which uperates on a straight line relationship will enable the operator of the machine to obtain instantaneous check-up on the performance of the machine which will thus indicate the presence of adverse conditions of operations which may not have been otherwise made apparent. The device will thus maintain a constant check on performance and act as a safety factor.

The preferred form of measuring the ratio of engine speed and fluid flow has been herein shown but it must be understood that other means may be employed to indicate this ratio so long as the said means function in a manner proportional to the pressure in the pump casing. For instance the mean position of diaphragm operating stem 0 is proportional to the ratio to be derived and can be, indicated in various ways.

What we claim as our invention is:.

i. As a means for indicating the ratio of fuel consumed to distance travelled in' fuel enginepropelled vehicles the combination with a pump I supplying fuel to said vehicle propulsion engine, said pump having a casing having a pump element operating therein in one direction by said engine at a rate fixed in relation to the enginespeed to create a fuel flow to the engine, valve means controlling the inlet and outlet of 'fiuid' pump element'during periods of cessation of the former movement, the said spring means acting to control the pressure in accordance with the engine fuel requirement, of means infiuentially: con-v. nected with the pump chamber defined by the operated pump element, the valves, and the pump casing and indicating through the mean pressure therein the ratio'between the fuel requirements and distance travelled, by the vehicle.

' 2. As a means for indicating the ratio of fuel consumed to distancetravelled in fuel engine-v "propelled vehicles',the combination with a'pump 'mllplying fuel to said vehicle propulsion engine,

said pump having a diaphragm periodically operated in one direction bythe vehicle propulsion engine, a lost-motion device permitting lost -motion between the engine and the diaphragm,

,the purpose of indicating the ratio of fuel can'- sumed to the distance travelled by the vehicle,

7 and pressure damping means disposed between the said pressure producing side of the pump diaphragm and the gauge to dampen out the pulsations in the pressure created by the movements of said diaphragm.

. WILLIAM F. BU'I'HERLAND.

GRIFFIN G. WAITE. 

